nvidia cards are quite common, so one hopes this major limitation can be worked around. Perhaps we should get Torvalds to comment in his inimitable style on the situation.
(The workaround is to use the nouveau driver, which is fairly capable as long as you're not trying to play 3D games)
For me the thought of losing nvidia driver support on Ubuntu is rather scary given the current state of all other 3D drivers (and certainly other Distro's might follow with Wayland). I hope the status of other drivers improves a lot before that switch or 3D on Linux will be set back a lot.
Also, given the number of people using Nvidia drivers on Ubuntu, my guess would be that Ubuntu will not switch to Wayland until the compatibility issue is solved.
The X11 and Linux display landscape has changed dramatically over the last few years. I think that nVidia chose the wise strategy of "wait and see" to pinpoint what stabilizes and have since been working on porting pieces of their proprietary driver. The recent addition of XRandR 1.2+ support probably has more to do with the announcement of Optimus development than anything else, and this work is probably a precursor to a version that supports KMS and the other technologies that will be required for compatibility into the next five years of Linux desktop.